concat_pdf_even.py

import subprocess
from pathlib import Path
from PyPDF2 import PdfReader, PdfWriter

outPdf=PdfWriter()
for inf in Path.cwd().glob("*.html"):
    pdff = inf.with_suffix(".pdf")
    if not pdff.exists():
        print(f"*1* {inf} -> {pdff}")
        subprocess.check_call(["wkhtmltopdf", str(inf), str(pdff)])
    with open(pdff, 'rb') as input:
        pdf=PdfReader(input)
        outPdf.append(pdf)
        if len(pdf.pages) % 2:
            outPdf.add_blank_page()

outPdf.write("out.pdf")